Improved Short-Term Clock Prediction Method for Real-Time Positioning

Lv, Yongfeng; Dai, Zhiqiang; Zhao, Qile; Yang, Sheng; Zhou, Jinning; Liu, Jingnan

doi:10.3390/s17061308

Cited by 24 publications

(12 citation statements)

References 18 publications

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“…The short-term clock prediction can also reflect the stability of the satellite clock, and it can be used for real-time applications such as real-time precise point positioning (RT-PPP) [33,34]. Therefore, short-term clock prediction is also conducted.…”

Section: Methodsmentioning

confidence: 99%

Characteristics and Performance Evaluation of QZSS Onboard Satellite Clocks

Xie

Huang

Cui

et al. 2019

Sensors

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In the Global Navigation Satellite System (GNSS) community, the Quasi-Zenith Satellite System (QZSS) is an augmentation system for users in the Asia-Pacific region. However, the characteristics and performance of four QZSS satellite clocks in a long-term scale are unknown at present. However, it is crucial to the positioning, navigation and timing (PNT) services of users, especially in Asia-Pacific region. In this study, the characteristics and performance variation of four QZSS satellite clocks, which including the phase, frequency, frequency drift, fitting residuals, frequency accuracy, periodic terms, frequency stability and short-term clock prediction, are revealed in detail for the first time based on the precise satellite clock offset products of nearly 1000 days. The important contributions are as follows: (1) It is detected that the times of phase and frequency jump are 2.25 and 1.5 for every QZSS satellite clock in one year. The magnitude of the frequency drift is about 10−18. The periodic oscillation of frequency drift of J01 and J02 satellite clocks is found. The clock offset model precision of QZSS is 0.33 ns. (2) The two main periods of QZSS satellite clock are 24 and 12 hours, which is the influence of the satellite orbit; (3) The frequency stability of 100, 1000 and 10,000 s are 1.98 × 10−13, 6.59 × 10−14 and 5.39 × 10−14 for QZSS satellite clock, respectively. The visible “bump” is found at about 400 s for J02 and J03 satellite clocks. The short-term clock prediction accuracy of is 0.12 ns. This study provides a reference for the state monitoring and performance variation of the QZSS satellite clock.

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Section: Methodsmentioning

confidence: 99%

Characteristics and Performance Evaluation of QZSS Onboard Satellite Clocks

Xie

Huang

Cui

et al. 2019

Sensors

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“…System) are widely used for navigation, positioning, scientific [1][2][3][4], and engineering applications [5][6][7]. That includes deformations [8][9][10] and structure monitoring [11][12][13], GIS (Geographic Information System) applications [14][15][16], land use [16][17][18][19], and cadastre [20][21][22][23][24].…”

Section: Gnss (Global Navigationmentioning

confidence: 99%

High-Rate Monitoring of Satellite Clocks Using Two Methods of Averaging Time

Maciuk

Lewińska

2019

Remote Sensing

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Knowledge of the global navigation satellite system (GNSS) satellite clock error is crucial in real-time precise point positioning (PPP), seismology, and many other high-rate GNSS applications. In this work, the authors show the characterisation of the atomic GNSS clock’s stability and its dependency on the adopted orbit type using Allan deviation with two methods of averaging time. Four International GNSS Service (IGS) orbit types were used: broadcast, ultra-rapid, rapid and final orbit. The calculations were made using high-rate 1 Hz observations from the IGS stations equipped with external clocks (oscillators). The most stable receiver oscillator was chosen as a reference clock. The results show the advantage of the newest GPS satellite block with respect to the other satellites. Significant differences in the results based on the orbit type used have not been recorded. Many averaging time methods used in Allan deviation (ADEV) show the clock’s fluctuations, usually smoothed in 2n s averaging times.

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“…Unfortunately, not all users can use the correction information due to either cost of the service or the user location is not within the coverage area of the service. Therefore, to improve the accuracy of predicted satellite clocks, especially over short-term, is of considerable interest to make RTPPP reliable in the abovementioned circumstances [10,11].…”

Section: Introductionmentioning

confidence: 99%

Improving Short Term Clock Prediction for BDS-2 Real-Time Precise Point Positioning

Zhou

Wen

et al. 2019

Sensors

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Although there are already several real-time precise positioning service providers, unfortunately, not all users can use the correction information due to either cost of the service and limitation of their equipment or out of the service coverage. An alternative way is to enhance the accuracy of the predicted satellite clocks for precise real-time positioning. Based on the study of existing prediction models, an improved model combing the spectrum analysis (SA) and the generalized regression neural network (GRNN) model is proposed especially for BeiDou satellite navigation system (BDS)-2 satellites. The periodic terms and GRNN-related parameters including length and interval of sample data, as well as a smooth factor, are optimized satellite by satellite to consider satellite-specific characteristics for all the fourteen BDS-2 satellites. The improved model is validated by comparing the predicted clocks of existing models and the improved model with precisely estimated ones. The bias of the predicted clock is within ±0.5 ns over three hours and better than that of the other models and can be used for several real-time precise applications. The clock prediction is further evaluated by applying clock corrections to precise point positioning (PPP) in both static and kinematic mode for eight IGS (International GNSS Service) MGEX (Multi-GNSS Experiment) stations in the Asia-Pacific region. In the static PPP, the improved model is validated to be effective, and position accuracies of some IGS MGEX stations achieve more than 30.0% improvements on average for each component, which enables us to obtain sub-decimeter positioning. In the kinematic PPP, the improved model performs much better than the others in terms of both the convergence time and the position accuracy. The convergence time can be shortened from 1–2 h to 0.5–1 h, while the position accuracy is enhanced by 15.4%, 21.6% and 19.3% on average in east, north and up component, respectively.

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Improved Short-Term Clock Prediction Method for Real-Time Positioning

Cited by 24 publications

References 18 publications

Characteristics and Performance Evaluation of QZSS Onboard Satellite Clocks

Characteristics and Performance Evaluation of QZSS Onboard Satellite Clocks

High-Rate Monitoring of Satellite Clocks Using Two Methods of Averaging Time

Improving Short Term Clock Prediction for BDS-2 Real-Time Precise Point Positioning

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